The LATE Paleozoic Era One Giant Leap for Evolution Charles Roelant Nicolas Ciccone
The Devonian Period • Known as the “Age of the Fishes” • Fish developed proper bone structures and jaws, and ostracoderms became more prevalent. Other fish formed lobed fins with pointed bones, which probably evolved into the legs of the first amphibians. • Lungfish such as Dipterus began to take form, allowing fish in a shallow pond to breath above water.
The Devonian Period • Invertebrates started to form reefs off the coast of the newly colonized land • The first wooded, seeded, and leafed plants developed on land during this era • The first insects made their homes among these new plants • Included lycophytes, sphenophytes, ferns, and progymnosperms
The Devonian Period • The first truly documented subduction zones occurred as the supercontinents Laurasia and Gondwana moved closer together toward the Equator. • Early drainage in the pre-Appalachians resulted in sand and mud formations in modern-day Canada and Maine. • These continents were gathered near the equator and were very warm, thus promoting the plant and animal life to grow. Source: paleoportal.org
The Carboniferous Period • This era is split into two epochs: Mississippian and Pennsylvanian • The latter is known as the Age of Coal Swamps • During the Pennsylvanian epoch • Bryozoans and brachiopods flourished • Many of the older species started to die out, i.e. trilobites, placeoderms, coral • Several of these, including algae, became limestone deposits
The Carboniferous Period (Pennsylvanian) • On land, the insects Meganeura and Arthropleura, the ancestors of dragonflies and millipedes, grew to enormous size. The reason for this growth was the oxygen-rich atmosphere (35% oxygen, as opposed to today’s 21%) that resulted from exposure to the sun at the equator. Four-legged tetrapods evolved along the shorelines, and included amphibians (“half-life”), who moved from the water to the land during the course of their lives, and reptiles, who formed a leather skin to help them withstand the extremities in climate. These creatures’ developments were aided by their birth in amniotic eggs, which appeared for the first time.
The Carboniferous Period (Pennsylvanian) • Lush, green, carbon-rich swamps grew from lycopsids, and remained in present-day North America, northern Europe, and Asia. http://www.geology2.pitt.edu/GeoSites/coal%20swamp.jpg
The Permian Period and the End of an Era • The greatest evolutionary age ended with the greatest disaster • As the continents shifted to form Pangaea they moved away from the equator • Caused a severe drop in temperature • Killed off a majority of the amphibians and reptiles that couldn’t adapt to the changing climate • 90% of all aquatic life died and 70%of all land vertebrates
The Permian Period and the End of an Era • From this period, however, there emerged more reptiles (Pelycosaurs and Dimetrodons) and the ancestors of the first mammals, therapsids…